title: Metagenomics for NoV surveillance: Test Set Sample sequencing
description: For Norovirus (NoV) genomic surveillance, metagenomics sequencing of viral nucleotides captured by VirCapSeq-VERT probe set, was performed. This metagenomics approach, in theory agnostic, offers the great advantage of unbiased detection of NoV, including the detection of novel NoV recombinants. Samples come from three different sequencing sets - Baseline Survey (BLS) samples, Outbreak-related (OB) samples, and two synthetic Test Set samples (TSS1 and TSS2). The TSS1 samples were prepared by mixing equal quantities (in terms of NoV genome copies) of nucleic acids extracted from selected norovirus-positive human stool samples. This mix is serially diluted to reach concentrations of 10^3, 10^2, and 10^1 genome copies of each norovirus strain per microlitre of extract. TSS1 contains the 12 NoV strains, namely 8 strains belonging to GII and 4 belonging to GI. 8 NoV GII and 4 NoV GI strains, representing 7 different GII genotypes for VP1 and RdRp, and 4 different GI genotypes for VP1 and RdRp were selected, covering phylogenetically distant NoV genotypes. Strains belonging to NoV GII.4[P16], GII.4[P31], and GII.17[P17] genotypes were selected in priority due to their high frequency in the European human population since 2016 (Noronet unpublished data, search date 19-01-2019) (https://www.erasmusmc.nl/en/research/projects/Noronet).